An in-vehicle emergency report apparatus mounted in a vehicle has a backup battery including a rechargeable battery, such as a lithium ion battery, and operates with the backup battery even when a vehicle battery damages in a traffic accident, for instance. The backup battery has a characteristic that its discharge performance decreases at low temperatures. For example, the discharge performance at −30 degrees centigrade is about one-fourth that at 0 degrees centigrade. Thus, a vehicle needs to adopt a backup battery efficient enough to secure the discharging performance at low temperatures. Such a backup battery exhibits the discharge performance much higher than needed at usual temperatures, leading to high costs in usual usage (refer to JP 07-243693 A).